Electron device



May 21, 1935. F. B. MacLAREN ELECTRON DEVICE Filed Dec. 16, 1929 2 Sheets-Sheet l Ju /6&4;

, w l f Z May 21, 1935. F, B MacLAREN 2,002,207

ELECTRON DEVICE Filed Dec. 16, 1929 2 Sheets-Sheet 2 IN VVVV OR Patented May 21, 1935 UNITED STATES PATENT OFFICE mesne assignments,

to Revelation Patents Holding Company, a corporation of Delaware Application December 1 26 Claims.

This invention relates to electron devices and particularly to such devices as are used as amplifiers to increase electrical impulses as in a radio receiving set or in sound motion picture work.

In electron devices now in use for this type of work the power output of the device is somewhat limited. Also in order to get undistorted output with such devices it is necessary to apply a negative bias to the control electrode thereof.

It is therefore, one of the objects of the invention to provide a thermionic tube which has a large power output.

Another object of the invention is to provide a thermionic tube in which the positive swing of the grid may be utilized to produce undistorted amplification.

Another object of the invention is to provide a thermionic tube which will give undistorted output without grid bias.

Another object of the invention is to provide a thermionic tube with an auxiliary grid-cathode unit therein not connected with any elements of the tube or with the terminals thereof.

Other objects of the invention and objects relating to the method of constructing and assembling the various parts and connecting the parts together will be apparent as the description of the invention proceeds.

Several embodiments of the invention have been illustrated in the accompanying sheets of drawings in which:

Fig. 1 is a diagrammatical view of the tube and the circuit therefor;

Fig. 2 is a sectional front elevation of one embodiment of the invention which maybe preferred;

Fig. 3 isa plan view of the elements shown in Fig. 2;

Fig. 4 is a sectional front elevation of another embodiment of the invention;

Fig. 5 is a plan view of another embodiment of the invention;

Fig. 6 is a plan view of still another embodiment of the invention;

Fig. 7 is a diagram of a modified circuit. for the invention; and

Figs. 8 and 9 are diagrammatical views of the invention used in connection with a four terminal base.

In general the invention comprises a thermionic tube which has two cathodes and two grids, one of each being an auxiliary electrode, anda single anode. One of the grids acts as an input grid similarly to the grid of any ordinary thermionic tube and one of the cathodes acts as 6, 1929, Serial No. 414,287

an ordinary cathode. The anode is adapted to be connected to the output circuit similarly to the ordinary tube. The auxiliary cathode is connected to the auxiliary grid so that these two parts are electrically connected together but are entirely independent of any of the other elements. The first grid may be mounted adjacent the auxiliary cathode while the auxiliary grid may be mounted adjacent the first cathode, the anode surrounding all of the electrodes.

Referring more specifically to Fig. 1 of the drawings in which the circuit diagram of the construction is shown an envelope II] has within it a grid ll, an anode l2, and a cathode l3. These three elements operate somewhat similar to the grid, anode, and cathode of an ordinary electron tube, but the action is varied by the insertion of an auxiliary cathode and grid. The auxiliary cathode I4 emits electrons to the anode l2 and this electron stream is controlled by the grid I I. An auxiliary grid I5 is connected directly to the auxiliary cathode I 4 and controls the electron emission from the cathode l3 to the anode l2. A heater l6 may be provided to heat the cathode l4 and a heater I! may be provided to heat the cathode l3 and these heaters may be arranged in parallel, if desired, or in series, or a single heater may be used for both as will be described hereinafter.

, Two wires I 8 may lead out of the envelope from the filament and connect to the secondary IQ of a transformer 20, the primary 2| of which is connected to an alternating current power source. The grid ll may be connected by means of a wire 22 to the secondary of an input transformer 24, as is customary in the art, and the anode l2 may be connected by means of a wire 25 to the primary 26 of an output transformer 21. The other end of the secondary 23 of the input transformer 24 may be connected by means of a wire 23a to the negative of a B battery 28 while the positive side of the B battery may be connected to the other end of the primary 26 of the output transformer 21. The cathode l3 may be connected by means of the wire 29 to the wire 23a which is connected to the nega- 4 tive side of the B battery and a condenser 30 may be connected across the B battery to permit the feedback from the anode in a manner wellknown in the art.

I believe the theory of operation of the device as just described may be somewhat as follows: Signals impressed upon the input of the transformer 24 cause a variation in the secondary 23 and, therefore, a potential variation of the grid II.. The grid I I influences the electron emission from the cathode l4 and as this cathode is directly connected to the grid l5 the latter controls the output of the tube as it controls the electron emission between the cathode l3 and the anode I2. I As described in my Patent No. 1,959,540, issued May 22, 1934, when the grid l5 swings negatively due to a'negative potential on the grid II which is transferred to the grid I5 by virtue of the change in the electron stream from the cathode l4 which is connected to the grid I5, the tube will amplify undistorted signals similarly to any electron tube now in use. However, when the grid 15 becomes positive due to a positive swing of the grid H, electrons which are emitted to the grid 15 from the cathode l3 cause a current to flow between the grid l5 and the cathode l4 in the same direction which is normally taken by the current caused by the electron emission from the cathode l4 to the anode l2. As the cathode I4 is connected to the grid l5 it is more positive than the cathode I3 and, as the latter is connected through the outside circuit to the grid II, the cathode I4 is more positive than the grid II, and hence even though the grid II is positive no current will flow in the input circuit through the secondary 23 of the transformer 24. Therefore, when the grid II is negative no current will fiow in the input circuit, as is well-known in the art, and when the grid II is positive no current will flow due to the auxiliary cathode l4 and grid I5.

Thus the tube of the present invention amplifies Without distortion as the grid swings between positive and negative. While this explanation of the theory of operation of the invention may not be correct I have been led to believe that it works in this manner. In any case the tube amplifies and gives a greater power output than the average tubes now in use and the swing of the potential on the grid need not be limited as by a negative grid bias.

In Figs. 2 and 3 I have shown one way in which the various elements of the tube may be mounted. An anode 3| corresponding to the anode l2 of Fig. 1 may be formed of a flattened tube of sheet nickel or other metal with the other elements supported within it. A grid 32 corresponding to the grid ll of Fig. 1 is formed'of a helical coil of molybdenum or other wire positioned within the anode, extending longitudinally thereof, and spaced from the walls thereof. Inside of the grid 32 I provide a cathode 33 which is preferably a cylinder of nickel or other desirable metal coated with an electron emitting material. This cathode is connected by means of a wire 34 to a second grid 35 which is arranged parallel to the grid 32 and comprises a similar coil mounted with the anode 3| as clearly indicated in Figs. 2 and 3. Within the grid 35 I provide a cathode 36 which may be similar to the cathode 33 already described.

The cathodes 33 and 36 may be heated in any desired manner but in the present instance I have shown two rods 31. and 38 of insulating material within the cathodes 33 and 36 respectively, each of these rods having a hole extending longitudinally through the center thereof through which a filament 39 may pass. A press 40 may be provided in the device and the elements may all be supported upon the press in any desirable manner, the electrical connections for the various elements being sealed therein. Thus the anode 3| is provided with an electrical connection 4|, the grid 32 with an electrical connection 42, the

cathode 36 with an electrical connection 43 all of which connections are sealed in the press and the two ends of the filament 39 may also be sealed in the press as indicated. This makes five connections so thatthe tube may be used to replace the five terminal tube now in use. The operation of this device is'similar to what has already been explained in connection with Fig. 1.

In Fig. 4 I have shown another embodiment of the invention in which a cylindrical anode 44 has within it a pair of helical grids 45 and 46 spaced apart longitudinally as indicated. The grid 45 corresponds to the grid II in Fig. 1 and may be connected to the external circuit by means of a lead 41. Within the grids 45 and 46 I provide cathodes 48 and 49 respectively having a length approximately equal to the length of the grid in each case. The cathode 48 corresponds to the cathode M of Fig. 1 and may be connected to the grid 46 by means of wires 50 as indicated. The cathode 49 may be connected to the external circuit by means of the wire 5|. Also the anode 44 may be connected to the external circuit by means of the wire 52.

In order to heat the cathodes 48 and 49 I provide an insulating rod 53 which extends completely through both of the cathodes, longitudinally thereof, and is provided with a pair of holes extending axially therethrough. A hairpin filament 54 is provided with one leg extending through one'hole and the other leg through the other in the insulator the end of each leg being connected to the external circuit by a plurality of wires 55. The operation of this construction is similar to what has already been described.

In Fig. 5 I have shown a still further modification of the construction shown in the preceding figures. A cathode 56 formed of a tube of nickel corresponds to the cathode I4 of Fig. 1 and is surrounded by a coil 51 forming the grid which corresponds to the grid ll of Fig. 1. Around this grid is positioned an anode 58 which is preferably in the form of a tube and corresponds to the anode l2 of Fig. 1. A second anode 59 considerably larger in diameter than the anode 58 is placed around the latter but is electrically connected to it by means of the wire 60 thus making a single electrical anode out of the two cylindrical anodes 58 and 59. Between these two anodes I preferably position a plurality of cathodes 6| each of which is surrounded by a grid 62. All of the cathodes 6| are connected together as by means of a wire 63 and these cathodes correspond to the cathode I3 of Fig. 1. All of the grids 62 are also connected to the cathode 56 as by wires 64 and these grids correspond to the grid I5 or Fig. 1.

In order to heat the cathodes 56 and 6| I provide insulating sleeves or rods through which the hairpin filaments are positioned as was described in connection with Fig. 4 and these filaments may be connected in parallel or in series as desired. Any desired number of the cathodes 6| and grids 62 may be used but I prefer to use six as indicated in the figures. The same theory of operation as has been described in connection with the other figures obtains in this case.

In Fig. 6 I have illustrated a still further embodiment of the invention. In this case a cylindrical cathode 65 is provided with a suitable heating means as the filament 66 and is surrounded by a helical coil of wire 61. This coil of wire is a combined cathode and grid taking the place of the cathode l4 and the grid I5 of Fig. 1.

Around this coil 61 I provide another helical coil 68 which is the grid corresponding to the grid I l of Fig. 1 and a cylindrical anode 69 is provided surrounding the grid 68. In this case the combined cathode and grid 61 receives enough heat from the first cathode 65 to cause it to emit electrons giving the same effect as the construction already described. I prefer to coatthe combined cathode and grid 61 with some material which will emit electrons at a lower temperature than is normally used as it depends for heat upon the first cathode 65 and will therefore, necessarily remain at a temperature lower than the cathode 65. Hence, if it is provided with a coating which is active at lower temperatures it will function similarly to the cathode ll of Fig. 1. I prefer to use caesiumas a coating material for this purpose.

The mesh of the combined grid and cathode is preferably much finer than the mesh of the outer grid so that the amplification constant of the outer grid is lower than the inner one.

I have found that a positive bias on the input grid is a desirable addition to the invention. As the input grid is nominally negative the positive bias will offset part of the negative bias already there and let the grid function over the straight line portion of the grid voltage-plate current characteristic curve. Such a grid bias may be made by means of the resistance 1| shown in Fig. '7, or a battery may be inserted in the transformer cathode lead with its positive terminal towards the grid ll.

The tube can also be mounted upon a four terminal base. by connectingthe cathode 13 directly to a portion of the heating circuit inside of the base tube as indicated in Fig. 8 or, if desired, to the mid-point of the filament, or a resistance I2 (Fig. 9) may be connected across the heater leads inside of the base and the cathode terminal may be connected to the mid-point of this resistance. This construction has the advantage that no plate current fiows through the filamentand, therefore, a tendency to overheat the filament is avoided.

The tube of the invention has more power output because the output impedance is very low and a very high amplification constant may be used without increasing the impedance greatly. The limiting factor in the operation of the tube is the high temperature of the anode because of high plate current. This can however, be brought to a reasonable amount by increasing the amplification constant and letting the plate current swing by a large amount.

While the invention has been shown and described in connection with an alternating current source of. heater energy it is evident that the tube will also operate on direct current or any other means of heating the cathode may be resorted to. The tube may be also used for amplifying either radio or audio frequency currents and also as an oscillator or modulator, or detector.

It will be evident from the above that I have provided an electron tube having four or five terminals so that it may be substituted for the standard alternating current tube now in use which will produce a greater power output as it is not necessary to limit the swing of the grid potential in the incoming circuit.

Modifications of the invention may be resorted to without departing from the spirit thereof, and I do not therefore, desire to limit the invention to what has been shown and described except as such limitations occur in the appended claims.

wire sealed-in said press and connected to said grid, a tubular cathode within said grid, a second tubular grid within said anode and spaced from said first grid, a wire connecting said second grid directly with said cathode, a second cathode within said second grid, a wire sealed in said press and connected to said second cathode, and a heating filament adjacent said cathodes to heat them to an electron emitting temperature.

2. An electron device comprising a grid, a cathode connected directly to said grid, 9. second grid adapted to influence the electron emission from said cathode, a second cathode adjacent said first grid whereby the electron emission thereof is influenced by said first grid, and an anode adapted to receive electron emission from both of said cathodes.

3. An electron device comprising a cathode, a tubular grid surrounding said cathode, a tubular anode surrounding saidgrid, a plurality of cathodes positioned adjacent the outer surface of said tubular anode, a tubular grid surrounding each of. said tubular cathodes, said grids being all connected to said first mentioned cathode, and a second tubular anode surrounding said plurality of cathodes and grids and connected to said first mentioned anode.

4. An electron device comprising an electron emitting cathode, an insulated coil of wire surrounding said cathode and acting as a combined secondary cathode and grid, a tubular grid surrounding said coil, and a' tubular anode surrounding said grid to receive the electrons emitted by both cathodes.

5. An electron device comprising a cathode, an insulated coil of wire surrounding said cathode and acting as a combined secondary cathode and grid, a coating on said coil adapted to emit electrons at a lower temperature than said cathode, atubulargrid surrounding said coil, and a tubular anode surrounding said grid.

6. An electron device comprising a tubular anode, a tubular grid within said anode, a tubular cathode within said grid, a second tubular grid within said anode and spaced from said first grid, said cathode and second grid being directly connected together electrically, a second cathode within said second grid, and means to heat said cathodes.

7. An electron device comprising a tubular anode, two tublular grids within said anode and spaced therefrom and'from each other, and a tubular cathode within each of said grids, one of said cathodes being directly connected to one of said grids but insulated from the other'eiements.

8. An electron device comprising, a tubular anode, a pair of tubular grids mounted within said anode and longitudinally spaced from each other, and a pair of cathodes, one within each grid, one of said cathodes being directly connected to one of said grids.

9. An electron device comprising a tubular anode, a second tubular anode within said first anode and spaced therefrom and connected electrically thereto, a cathode within said second anode, a grid between said second anode and cathode, a plurality of cathodes positioned between said anodes, and a plurality of grids, one adjacent each of said last mentioned cathodes, said last mentioned grids being connected together and to said first mentioned cathode, and

said cathodes between said anodes being con-' nected together;

.10. An electron discharge tube comprising an evacuated envelope, 9. first cathode, a grid positioned to influence the electron emission from said cathode, a second cathode, a grid positioned to influence the electron emission from said second cathode, said second grid being directly connected to said first cathode, and an anode for each of said cathodes.

11. An electron discharge tube comprising an evacuated envelope, a first cathode, a grid positionedto influence the electron emission from said cathode, a second cathode, a grid positioned to influence the electron emission from said second cathode, said second grid being directly connected to said first cathode, an anode positioned to' receive electrons emitted from said first cathode, and an anode positioned to receive the electrons emitted from said second cathode.

12. An electron discharge device according to claim 11 in which the said anodes are electrically connected.

13. An electron discharge device comprising an evacuated envelope, a first-cathode, a grid positioned ,to influence the electron emission from said cathode, a second cathode, a grid positioned to influence the electron emission from said second cathode, anodes for said grids, and a direct metallic connection between the said first mentioned cathode and the second mentioned grid. 14. A vacuum tube comprising an envelope containing a cathode, a grid and a plate element,

another cathode, grid and plate element, a heater element for indirectly heating said cathodes, said second mentioned-grid being directly connected with the first mentioned'cathode.

15. A vacuum tube comprising an envelope containing a cathode, a grid and a plate element,

another cathode, grid and plate element, a heater element for indirectly heating said cathodes, said second mentioned grid being directly connected with the first mentioned cathode, and means for electrically insulating the first mentioned cathode from the second mentioned cathode.

16. A vacuum tube comprising, an envelope containing a cathode; a grid and a plate element, another cathode,- grid and plate element, a heater element for indirectly heating said cathodes, the

first mentioned grid offering a higher impedance than the second mentioned grid, said second mentioned grid being directly connected with the first mentioned cathode, and means for electrically insulating the first mentioned cathode from the second mentioned cathode.

lfl. An electron discharge device comprising an envelope containing a plurality of triode units,

' each unit consisting of an electron emission element, a grid element-and a plate element, the grid element of one unit being connected to the electrornemission element of another unit.

18. An electron discharge device comprising an envelope containing a plurality of triode units, each unit consisting of an electron emission element, a grid element and a plate element, an electron emission element heatenthe grid element of one unit being connected to the electron emission element of another unit.

19. An electron discharge device comprising an envelope containing a plurality of triode units, each, unit consisting ofan electron emitter, a grid and a plate, said electron emitters being insulated from each other, the grid of one triode being connected to the electron emitter of another triode unit.

20. An electron discharge device comprising an envelope containing a plurality of triode units, each unit consisting of an electron emitter, a grid and a plate; said electron emitters being insulated from each other, an electron emitter element heater, the grid of one triode unit being connected .to the electron emitter of another triode unit.

21. An electron discharge device comprising a first-electron emitting cathode, a second electron emitting cathode, a first grid positioned to tron emitting cathode, a first grid positioned to influence electron emission from said first oathv30 first electron emitting'cathode, a second ele'c-y ode, a second grid positioned to influence elec- 3 tron emission from said second cathode, said- ,second cathode and said first grid forming the terminals of an input circuit for said device, said first cathode and said second grid being connected together to provide a pair of serial space paths inside said device between said second cathode and said first grid.

23. An electron device comprising an electron emitting cathode, means to heat saidcathode, a mesh of wire positioned to receive heat from said cathode but not metallically connected to said cathode, the surface of said mesh being treated to emit electrons, and said mesh acting as acombined secondary cathode and grid to influence emission from said cathode, another grid positioned to influence the electron emispositioned to receive electrons from said cathode and said secondary cathode.

24.'An electron discharge device according to claim 22 in which a single anode is positioned to receive electrons from the mentioned cathodes.

25. An electron discharge device according to 50 sion from said secondary cathode, and an anode claim 22 wherein each grid is provided with a separate anode.

26. An electron discharge device according to claim 22 in which each, grid' is provided with a separate tubular anode surrounding the. same.

FRED. B. MAOLAREN. 

